Think Smart: A Neuroscientist's Prescription for Improving Your Brain's Performance (5 page)

Over an eleven-month period Pasinetti fed mice in his laboratory an amount of Cabernet Sauvignon equivalent to a daily five-ounce glass for women and two glasses for men. He then tested the ability of the mice to learn to navigate their way within a water maze. Those mice given the wine learned to navigate the maze faster and more accurately than mice drinking just water. In fact, they learned the maze so well that they could remember it when tested forty days later. Coincident with this, the brains of the wine-swigging mice contained decreased amounts of the toxic by-products (amyloid protein) associated with Alzheimer’s disease.

While resveratrol is the most likely element in red wine contributing to its beneficial effects on the brain, scientists don’t know a lot about its absorption and clearance from the body, its effect on the liver, or even the precise identities of its by-products. Even more important, nobody knows the minimum effective dosage. The resveratrol story contains several other loose ends along with a fatal flaw in its plot structure. Ninety-five percent of resveratrol is destroyed by the digestive system before it enters the circulation. In addition, a 150-pound person would need to drink many bottles (750 to 1,500) of red wine a day in order to achieve the equivalent dose of the imbibing mice—not an advisable scenario. So why not take resveratrol in the form of supplements instead? Before you decide to do that, you should consider the following facts about supplements.

More than half of adults in this country take some form of vitamin or mineral supplement at a total cost of $23 billion a year. The antioxidant market alone grew by 18 percent between 2005 and 2006. Yet there are several reasons for exercising caution with supplements.

First, there is increasing evidence that supplements, in general, aren’t as effective as eating foods containing vitamins and antioxidants in their natural form. Even in nature, only certain forms of the vitamins are biologically active. Of the eight different forms of vitamin E found in nature, only one (alpha-tocopherol) is extracted from the bloodstream—all other forms are excreted. What’s more, while powerful antioxidant and other properties can be demonstrated in the test tube, many scientists now question whether similar effects occur in the body. In addition, the natural balance of vitamins and antioxidants found in natural foods is difficult to replicate in the laboratory. Nor is the effect of a supplement necessarily identical to the effect of the natural vitamin. For instance, in a study comparing dietary vitamin E with vitamin E from supplements, only the dietary form reduced the risk of Alzheimer’s disease.

Second, some recent studies suggest that the ingredients of some supplements, if taken in excess, may even be harmful. Too much vitamin E, for instance, can thin the blood and increase the risk of bleeding and stroke, especially among people afflicted with high blood pressure. One study from Johns Hopkins revealed that taking 400 IU of vitamin E per day is associated with a higher risk of dying compared with getting vitamin E from food sources.

So far, such findings aren’t stopping people from scooping up large quantities of vitamin E, a trend that started in the 1980s. While almost nobody took vitamin E supplements in the 1980s, ten years later an estimated 23 million Americans were downing daily doses. Nor has there been any lessening of this trend.

Multivitamins—currently the most popular approach to vitamin supplementation—can also prove troublesome if taken in excess. “If one pill is good for you, two or more will be even better” certainly doesn’t hold true with multivitamins. Men taking more than one multivitamin a day increase their risk of prostate cancer by 32 percent.

Similar caveats hold for most supplements in healthy people. Unless you are suffering from a deficiency of a certain vitamin, you aren’t going to benefit by taking supplements containing that vitamin. But to be fair, all of this assumes that a person is eating an adequate diet—a faulty assumption among older adults.

“With so many people living longer, we’re entering into a new stage in our understanding of the older brain,” Cotman told me. “The older person’s brain needs at least as many vitamins and antioxidants as the brain of a younger person. And yet older people are more likely to be lacking them because their diet is often inadequate as a result of their tendency to skip meals and eat less in general. The older brain needs supplements because they help prolong life and extend the years of healthy living. Smokers and people who drink a bit more than they should are also likely to be deficient in omega-3 fatty acids and other needed vitamins and antioxidants. The older person eating an insufficient or faulty diet can derive a lot of benefit from supplements.”

So what practical conclusions can one draw about diet and the brain? Here’s a summary of the most commonly accepted dietary formula for maintaining optimum brain health: maintain low weight, cut way down on saturated fats, eat fish and other foods containing high amounts of omega-3 fatty acids, decrease your intake of red meats, take in more fruits and vegetables, drink red wine in moderation, and sensibly supplement your diet with vitamins and antioxidants.

While nutrition is probably number one in importance as a stimulator to brain development, exercise runs a close second. That wasn’t always true. I grew up as a member of a generation that made firm distinctions between mental and physical exercise. During my college and medical school education “jocks” were routinely made fun of; the smartest people (or those who earned the highest grades in school) usually did little exercise, rarely tried out for sports, and by today’s standards led physically inactive lives. Now all of that has changed for the good, thanks to the success of such scholar-athletes as New York Knicks NBA Hall of Fame winner and former U.S. senator Bill Bradley and Sebastian Coe, long-distance runner and British MP—among others. We now know that an optimally functioning brain goes hand in hand with general good health. And since the brain is a biological organ governed by the same factors as all other body organs (a need for oxygen, glucose, and other nutrients, along with adequate blood perfusion), physical exercise, which increases all of these things, plays a leading role in enhancing brain function.

According to recent findings, consistent aerobic exercise leads to the growth within the brain of new capillaries—the tiny vessels bathing the neurons with nutrients. Accompanying this is an increase in the number of interconnections between neurons and the number of brain cells in the memory-encoding hippocampus. These enhancements result from exercise-induced elevations in the levels of nerve growth factors such as brain-derived neurotrophic factor (BDNF) and other nutritive tonics. Since a physical workout increases all of these factors, the end result is a better connected, more adaptive brain capable of thinking better and faster, processing information more efficiently, and generally working better overall.

According to Arthur Kramer, working out of the Beckman Institute at the University of Illinois, older adults with a lifelong history of cardiovascular exercise have better-preserved brains than sedentary people of the same age. The structural preservation is greatest in the frontal, temporal, and parietal lobes—three of the most important areas of the brain for mental processing.

Activation of the prefrontal area focuses our attention inward on what we’re
thinking;
temporal and parietal activation focuses attention outward on what we’re
doing.
Because these areas are better preserved among exercisers, longtime exercise adherents of any age perform better than couch potatoes when it comes to memory and the ability to remain focused.

“Although physical fitness training broadly influences a variety of mental processes, the largest gains involve the executive control processes,” according to Kramer. “Interestingly, these are the processes that show substantial age-related decline.” These are also the processes that differentiate older from younger workers (as will be discussed in more detail in the chapter on compensating for age-associated brain changes). Both mental and physical exercises can narrow the age-related performance gap.

The most interesting aspect of Kramer’s research findings was the short time frame required to bring about these changes. “Only six months of regular aerobic exercise increases brain volume,” Kramer, a bearded and convivial middle-aged man, told me during a conversation following one of his well-attended lectures. “We have here a simple and inexpensive mechanism to roll back some of the normal age-related losses in brain structure. We now know that brain volume loss is not an inevitable effect of advancing age. Relatively minor changes in activity level can go a long way in offsetting and minimizing brain aging.”

Anyone of any age who walks three times a week for forty-five minutes will reap the following benefits: sustained levels of cerebral blood flow; an improvement in focused attention; increases in gray matter volume in regions of the frontal and temporal lobes; and restoration of some of the losses in brain volume associated with normal aging. In anyone over sixty, the benefits are even greater. A daily one-mile walk will reduce the likelihood of dementia by 50 percent.

Exercise also brings about positive changes in the brain’s chemical messenger system. For instance, an antidepressant drug that affects three of the brain’s main neurotransmitters (norepinephrine, epinephrine, and serotonin) works even better when combined with exercise. As a result, neuropsychiatrists like myself are now encouraging our depressed patients not only to take their medicines, but to become more physically active as well. Since exercise and antidepressant medication affect some of the same neurotransmitters (depending on which antidepressant is taken), an increase in exercise may allow for a reduction in dosage of the drug.

One final point that should prove even more persuasive to anyone who dillydallies about exercise: Exercising at least three times per week lessens the odds of coming down with Alzheimer’s disease. Specifically, you can decrease the likelihood from about twenty in a thousand to thirteen in a thousand. Further, the earlier in life you begin exercising, the faster the processing speed of your brain when you’re sixty-five years of age or older. This doesn’t mean that if you were physically active earlier in life that you don’t have to continue to exercise. But it helps explain why some middle-aged adults who aren’t currently physically active but who exercised when they were children or young adults remain mentally sharp in their later years. The question is: Why did they give up the exercise habit?

Although there isn’t a simple answer to that question, one contributor, in my opinion, is the basically boring nature of most exercise programs. In fact, the very term “exercise program” turns off many people (me included).

As an alternative to a “program,” consider working out using the Nintendo Wii video-game system.

The original Nintendo system with its thumb-driven controllers was designed for entertainment and provided no exercise opportunity for any part of the body other than the hand. But the new Nintendo Wii system (pronounced “we”) uses handheld motion controllers that require the player to employ the same arm and body motions used in real-life tennis, golf, bowling, baseball, and boxing. The controllers are precise enough to track and mimic the body movements employed by real players engaged in these different sports.

In Nintendo Wii tennis, for instance, you can return a shot via a lazy lob, but as in the real game, you’ll do a lot better if you hit the ball forcefully and precisely in response to the simulated tennis situation on the screen. Other games like bowling offer you the chance to compete against other participants. But whatever game you choose, the exercise benefits are much the same as those from real bowling, minus the subsequent aches and pains that are typically endured the day after holding and rolling a fourteen-to-sixteen-pound bowling ball.

WiiFit, a fitness-themed software program, is even more physically stimulating. For this program players stand on an electronic platform containing sensors that translate the pressure created by body motion into televised motion on the monitor. In a ski-jump program, for instance, the Wii skier has to squat down and spring up at the precise second that he reaches the end of the ramp. Precision and balance combined with physical endurance are demanded in the boxing program as players simultaneously weave, duck, and throw combination punches. Thanks to such a program, you can pretend you’re Oscar De La Hoya while sparing yourself the brain-jarring head punches associated with real boxing.

If you’re not drawn to such games, find the prospect of spending time in a health club less than thrilling, and don’t want to devote inordinate amounts of time and energy to exercise, you might want to try my personal exercise prescription:

At least three times a week I follow Arthur Kramer’s advice and walk for thirty to forty-five minutes at a brisk pace in different locations around Washington. By walking in varied neighborhoods I can combine exercise with learning more about the city. As I walk I remain fully alert to my surroundings; when I encounter something that interests me, I stop. This combination of physical with mental activity keeps me motivated in a way that a trip to a health club doesn’t. (To be fair, a health club offers opportunities for meeting other people and thus can serve as an antidote for loneliness, which is linked to Alzheimer’s disease.) But if loneliness or isolation isn’t a problem, you may find walking (perhaps combined with some jogging) to be your best means of getting the health benefits of exercise without being tethered to a repetitive, joyless routine.

Think of exercise according to a continuum model. At one end are those who claim that exercise is now an optional leisure activity, since it’s no longer necessary for physical survival (no more wild animals to elude). Not surprisingly, those who hold such views tend to be nonexercisers. At the other end of the spectrum are those intensely devoted exercisers who script their entire lives around exercise. Long-distance running is especially appealing to the latter group.